Earlier this week, at The People’s Pledge’s ‘Real EU debate’ in Westminster, I spoke in favour of Britain remaining in Europe. It was a lively event. Membership of the EU is an emotive issue, presented by Europhiles as a lifeline for the UK, and by Europhobes as a noose.

I believe, like countless others, that staying in Europe is the only way of securing Britain’s future prosperity. But for me these economic arguments run deeper, to the core question of what type of country we want to be.

It might be possible (if infinitely more difficult) for Britain to achieve prosperity outside the EU. But it would come at an enormous cost. To survive we would have to become more economically unfair and less globally significant – a poorer, more marginal country with narrower horizons.

The most immediate consequence of leaving Europe would be to effectively seal the fate of British manufacturing. As Nissan CEO Carlos Ghosn said last month, being part of the common market – to whom we sell around half our exports – is integral to businesses based in the UK. Outside of it we would become an “unattractive option” and companies like Nissan (which currently employs 6,500 at its Sunderland plant) would have to “reconsider” their strategy. It is likely that other firms, such as Airbus, would follow suit.

The financial sector, too, would struggle, and according to some commentators it would be difficult for The City of London to remain Europe’s business capital. Places closer to the heart of EU decision-making – such as Paris or Frankfurt – could take its place. Sir Martin Sorrell calls leaving Europe “disastrous”. He points out that Japanese investment in the UK is contingent on us staying in Europe. Trying to remain a trading centre while economically isolating ourselves would leave us permanently compromised.

In the longer term, with the EU currently working with the US to create the world’s biggest free trade area, Britain could become further marginalised. The CBI’s Director General John Cridland argues that being in Europe gives us a “springboard”, through unfettered trade agreements, with which to reach 500 million people and £15 trillion in profits. “We’d struggle to pull off deals of this scale on our own,” he says.

On top of this, the negative impact on higher education of Britain leaving Europe could be very serious. As Professor Paul White points out, this year we received 23% of EU Research Council Grants – more than any other country. Without this funding universities might have to downscale or increase fees – a move which would affect young people (the group, according to polls, who are least in favour of an EU exit) the worst. The insularity that withdrawal would bring could, White says, undermine our reputation as the second strongest higher education system in the world.

I therefore believe the notion we could leave the EU but carry on as normal is flawed. We would have to adapt. The only way I can see of doing this would be through a relaxation of tax rules and an effort to move from hub to haven. Big companies might be replaced by ‘boutique’ avoidance specialists and businesses enticed here by the chance to use the UK as a low tax trading base. The pressure on the government to reduce taxes – combined with the loss of the EU funding many of Britain’s regions receive – could create worse public services and more inequality. As David Marquand puts it, to survive Britain would have to become “a market state…a harder, more selfish and, above all, nastier society”.

So for me the Europe Question goes beyond prosperity; it relates to the deeper issue of who we are as a country. Do we want to embrace a fairer, more modern world or will we consign ourselves to narrow-minded irrelevance? I believe this is a no-brainer; as I will continue to argue all the way up to the European Elections in May, Britain needs to be confident and outward-looking enough to see the wood for the trees when it comes to Europe.